Tolls on the Interstate 70 Mountain Express Lane this winter never reached anywhere near the maximum $30, but state transportation officials said the option still saved all drivers time — even if they stayed in the free lanes.
In addition to smoother traffic, the 13-mile corridor also recorded fewer wrecks and shorter backups during its inaugural season, the Colorado Department of Transportation said Thursday in an end-of-season report.
The highest cost paid by 42,600 drivers who used the eastbound toll lane was $8 if they had an ExpressToll transponder, or $14.67 for those without one, including the license plate toll processing fee. More typical during the phase-in season were tolls between $4 and $6 (or $8.33 to $11.50 without a transponder), CDOT said.
There was a residual benefit for those who stayed in the free lanes, CDOT said: Average travel times were 18 percent shorter than in the last few winter seasons.
The express lane — a narrower lane added on the left shoulder from Empire to Idaho Springs — was open on 32 weekend days and holidays between mid-December and April.
During the ski season, traffic long has snarled in the corridor, especially on Sunday afternoons as daytrippers return to the Front Range. When it opened the express lane, CDOT aimed to control use with demand-based pricing, adjusting the toll to ensure that its users always would be able to stay above 45 mph, even if the adjacent free lanes were crawling.
Facing a limited budget, CDOT and its High Performance Transportation Enterprise (HPTE) opted for the express lane instead of a much costlier widening project to add another free lane or two. The project cost $72 million, using federal and state funds as well as a $24.6 million loan that CDOT intends to repay using the tolls.
CDOT has not yet compiled toll revenue totals, said Megan Castle, the HPTE spokeswoman, because billing is still out for some of the roughly 60 percent of users who were charged via license-plate tolling.
Though the toll lane by no means has solved the congestion issues, CDOT says the average eastbound travel time during peak hours through the corridor was 13.6 minutes, with an average speed of 53 mph.
Compared to the three previous winters’ average peak travel time, that’s about three minutes shorter.
But the biggest impact from the toll lane was illustrated on heavy-volume days.
On Jan. 31, the day with the slowest average speed this season, it took an average 17.5 minutes to travel through the corridor for all lanes, with an average moving speed of 41 mph. That was a Sunday when the Denver Broncos’ afternoon AFC Championship appearance likely prompted skiers and weekend travelers to head home earlier than usual. High demand resulted in the slowest average speed measured in the express lane all season, at 47 mph.
In previous seasons, it took as long as 44 minutes to drive the 13 miles on the worst days, with traffic crawling at an average 16 mph, CDOT says.
The improvement held on Martin Luther King Day in January, too, with a reduction in travel time of up to 52 percent, according to CDOT.
And CDOT said that on April 3, when the express lane was open for 11 hours on a particularly busy Sunday, 34,136 vehicles traveled through the corridor in all lanes during that time. CDOT says such heavy volume normally would have resulted in crawling traffic, but at that day’s afternoon peak, average lane speeds stayed near 55 mph in the express lane and at 40 mph in the two free lanes.
“With the express lane this year, the corridor had normal travel times (even) with traffic volumes that would’ve collapsed the corridor with speeds of 5 to 10 mph in previous years,” said Margaret Bowes, director of the nonprofit I-70 Coalition, which represents local governments and businesses along the corridor, in a news release. “People can spend less time travelling and more time at their destinations.”
CDOT says it likely will keep the express lane closed during the mountain mud season until Memorial Day weekend.
Under its agreement with federal transportation officials, CDOT can open the express lane only 73 days per year, since it’s still considered a shoulder lane. With 44 percent of that allotment used up, the rest are reserved for the summer travel season, when I-70 gets even more use than in the winter and heavier traffic stretches out over more hours of the day, especially on holiday weekends.
That means the biggest test of the I-70 express lane still may be yet to come.
Jon Murray: 303-954-1405, jmurray@denverpost.com or @JonMurray
